Illumination apparatus confining light by total internal reflection and methods of forming the same
In various embodiments, an illumination apparatus includes an air gap between a sub-assembly and a waveguide attached thereto at a plurality of discrete attachment points, as well as a bare-die light-emitting diode encapsulated by the waveguide.
1. A method of forming an illumination device incorporating a light-emitting diode (LED) disposed on a sub-assembly, the method comprising:
providing a waveguide defining a recess in a first surface thereof;
positioning the LED at least partially within the recess such that an air gap separates the sub-assembly from the first surface of the waveguide; and
filling at least a portion of the recess with an index-matching material, the index-matching material being disposed around at least a portion of the LED.
2. The method of claim 1 , wherein at least a portion of the index-matching material is disposed within the recess before the LED is positioned at least partially within the recess.
3. The method of claim 1 , wherein positioning the LED at least partially within the recess comprises attaching the sub-assembly to the first surface of the waveguide at only one or more discrete attachment points.
4. The method of claim 3 , wherein at least one discrete attachment point is disposed on an elastically deformable relief defined at least in part by a relief trench extending through at least a portion of the sub-assembly.
5. The method of claim 3 , wherein attaching the sub-assembly to the first surface of the waveguide at only one or more discrete attachment points comprises dispersing an adhesive between the sub-assembly and the waveguide proximate at least one discrete attachment point.
6. The method of claim 1 , wherein the waveguide defines one or more protrusions from the first surface.
7. The method of claim 1 , wherein at least a portion of the index-matching material is disposed around the LED before the LED is positioned at least partially within the recess.
8. The method of claim 1 , wherein, after the at least a portion of the recess is filled with the index-matching material and the LED positioned at least partially within the recess, a free surface of the index-matching material is substantially coplanar with the first surface of the waveguide.
9. The method of claim 1 , wherein, after the at least a portion of the recess is filled with the index-matching material and the LED positioned at least partially within the recess, a free surface of the index-matching material is not coplanar with the first surface of the waveguide.
10. The method of claim 1 , wherein, after the at least a portion of the recess is filled with the index-matching material and the LED positioned at least partially within the recess, a free surface of the index-matching material is substantially parallel to the first surface of the waveguide.
11. The method of claim 1 , wherein, after the at least a portion of the recess is filled with the index-matching material and the LED positioned at least partially within the recess, he index-matching material is not in contact with the sub-assembly.
12. The method of claim 1 , wherein an index of refraction of the index-matching material is between an index of refraction of at least a portion of the LED and an index of refraction of at least a portion of the waveguide.
13. The method of claim 1 , further comprising positioning a reflector over at least a portion of a second surface of the waveguide to confine light within the waveguide.
14. The method of claim 13 , wherein the second surface is opposite the first surface.
15. The method of claim 13 , wherein an air gap is disposed between the second surface of the waveguide and the reflector.
16. The method of claim 1 , wherein the waveguide comprises therein or thereover an in-coupling element for in-coupling light emitted by the LED into the waveguide.
17. The method of claim 16 , wherein the in-coupling element comprises at least one of a reflector, a prism, or one or more scattering elements.
18. The method of claim 1 , wherein the LED comprises a bare-die LED.
19. The method of claim 1 , wherein the waveguide comprises, opposite the first surface, an emission surface for emitting light in-coupled into the waveguide.
20. The method of claim 19 , wherein the first surface and the emission surface are substantially planar.